Although it is generally known that blacks experience higher levels of morbidity and mortality than whites, very little is known about the reasons for these differences. The existence of a black-white 'mortality crossover' occuring after age 70 has been noted in several studies, but, again, very is known about the health of older blacks or the reasons for the crossover. It is generally assumed that higher risk factor levels and lower SES in blacks 'select out' more vulnerable members of the black population. However, little research has been done to examine this assumption. The proposed analyses will help to clarify the roles played by physiologic, sociodemographic and psychosocial risk factors in black-white differences in health at older ages. These analyses will be based on two large and unique datasets. The first includes 25,000 Kaiser Health Plan (KHP) members aged 50-74 who took a Multiphasic Health Checkup in 1971 or 1980. Equal numbers of blacks and whites, 12,500, will be included. Ten-and twenty-year mortality data, hospitalizations, consoderable risk factor information and psychosocial data will be available. The second database involves two 3000-person cohorts of KHP members who were aged 65 and over in 1971 or 1980. Data on the prevalence and incidence of over 26 chronic conditions has been collected and will be available for the 600 blacks and 5400 whites included in these two cohorts. In the second set of analyses, black-white differences in the duration of survival with chronic diseases will be examined. This will be the largest study ever done of black-white differences in mortality with substantial risk factor information and long-term follow-up.